ACIDSBASES ACIDS, BASES, & SALTS

Acids Properties of Acids 1.Sour taste 2.Electrolytes – aqueous solutions conduct an electric current 3.React with bases to form water and a salt. (Neutralization Reaction) 4.React with most metals to produce H 2 (g) dd 5.Acids turn litmus red

Electrolyte Substance that dissolves in H 2 O to produce a solution that conducts an electric current. Acids, bases, & salts are electrolytes – form ions in H 2 O. NaCl(s)  Na + (aq) + Cl - (aq)

Testing Conductivity Conductivity test Animation Strong electrolyte: animation Metal Wax

Which metals react with acids? See Table J. All the metals above H 2 react with acids. Cu, Ag, and AunotCu, Ag, and Au do not react with acids.

2HCl + Mg  MgCl 2 + H 2 Mg is above H 2 in Table J so reaction proceeds. Single replacement Redox

Bases Properties of Bases 1.Bitter taste 2.Slippery or soapy feeling 3.Electrolytes 4.React with acids to produce water and a salt 5.Bb 5.Bases turn litmus blue

Formulas of Acids H orGeneral format = HX where X is a nonmetal such as F, Cl, Br, I or X is a negative polyatomic ion (Table E) HSome acids have 2 or 3 H’s HHHEx: HF, H 2 S, H 3 PO 4 Organic Acids: format = R-COOH where R is C x H y

Formulas of Bases OHGeneral Format = MOH where M is a metal. OHOHEx: NaOH, Ca(OH) 2 NH 3 is the exception – it’s a base, too. NOTCH 3 OH is NOT a base. WHY?

Electrolytes Substances that conduct when dissolved in water. Acids: start with H or end in COOH Bases: M-OH or NH 3 Salts: Metal + Nonmetal

Identify the Electrolytes NaClNaCl C 2 H 5 OHC 2 H 5 OH H 2 SO 4H 2 SO 4 NaOHNaOH C 6 H 12 O 6C 6 H 12 O 6 CaI 2CaI 2 HFHF Mg(OH) 2Mg(OH) 2 C 3 H 7 OHC 3 H 7 OH CCl 4CCl 4 HNO 3HNO 3 C 5 H 12C 5 H 12 K 3 PO 4K 3 PO 4 CH 3 OCH 3CH 3 OCH 3 LiOHLiOH HIHI (NH 4 ) 2 SO 4(NH 4 ) 2 SO 4 C 12 H 22 O 11C 12 H 22 O 11 Yes - S NO NO NO NO NO NO NO Yes - A Yes - B Yes - A Yes - B Yes - A Yes - B Yes - A

Acid, Base, or Neutral? Turns out – all H 2 O contains some H + and some OH - Pure H 2 O – concentrations are very low. [H + ] = [OH - ] = 1 X Molar. When [H + ] = [OH - ], solution is neutral. Acidic solution: H + > OH - Basic solution: OH - > H +

Water & self-ionization H 2 O(l) + H 2 O(l)  H 3 O + (aq) + OH - (aq) H 3 O +H 3 O + is called hydronium ion OH -OH - is called hydroxide ion H 2 O(l)  H + (aq) + OH - (aq) In reality, H + and H 3 O + are used interchangeably. H +H + is called a proton or a hydrogen ion.

Self-ionization of water

Draw the Dot Diagram showing the Autoionization of H 2 O Rem: Hydrogen atoms contain 1 proton and 1 electron. H + contains only 1 proton, so it can be referred to as either a hydrogen ion or as a proton. H 3 O + is called hydronium ion.

Arrhenius Acid H +Substance that contains hydrogen & ionizes to produce H + as the only positive ion in aqueous solution. H +HCl(g)  H + (aq) + Cl - (aq) H +HNO 3  H + (aq) + NO 3 - (aq)

Arrhenius Base OH -A substance that contains a hydroxide group & ionizes to produce OH - as the only negative ion in aqueous solution. OH -NaOH(s)  Na + (aq) + OH - (aq)

Arrhenius Salt Electrolytes where H + is not the only positive ion and OH - is not the only negative ion in aq. solution. Ex: NaCl, CaBr 2,KNO 3, NH 4 I

Salts in Water NaCl(s)  Na + (aq) + Cl - (aq) CaBr 2 (s)  Ca +2 (aq) + 2Br - (aq) KNO 3 (s)  K + (aq) + NO 3 - (aq) NH 4 I(s)  NH 4 + (aq) + I - (aq)

Arrhenius Model has limitations Don’t always use H 2 O as the solvent. Arrhenius model only applies when H 2 O is the solvent. Doesn’t explain all cases: –NH 3 doesn’t contain OH - but it produces OH -.

Ionization of Acid: Arrhenius HCl  H + + Cl - HBr  H + + Br - HNO 3  H + + NO 3 - Looks like a salt falling apart, so it can also be called dissociation.

Ionization of Base: Arrhenius NaOH  Na + + OH - LiOH  Li + + OH - KOH  K + + OH -

Alternate Theory: Bronsted-Lowry Acid = a proton donorAcid = a proton donor All Arrhenius acids are Bronsted- Lowry Acids. HX(g) + H 2 O(l)  H 3 O + + X - H + H 3 O + hydronium ionH + forms a molecule-ion bond with the water molecule  H 3 O +, named hydronium ion.

Ionization of Bronsted-Lowry Acids HCl + H 2 O  H 3 O + + Cl - HNO 3 + H 2 O  H 3 O + + NO 3 - H 2 SO 4 + H 2 O  H 3 O + + HSO 4 - HSO H 2 O  H 3 O + + SO 4-2

Bronsted-Lowry Base Base = proton acceptor.Base = proton acceptor. OH - is a base. H + + OH -  H 2 O Not restricted to aqueous solution. NH 3 + H 2 O  NH OH - NH 3 is a base!

Amphoteric Substance that can act as both an acid & a base Water is amphoteric HX(g) + H 2 O(l)  H 3 O + + X - } H 2 0 = base NH 3 + H 2 O  NH OH - } H 2 O = acid

Water is amphoteric!

Movies Acid Movie Base Movie Electrolyte Movie Strong vs. Weak Electrolyte Movie

Vocabulary Interlude Monoprotic AcidMonoprotic Acid – has 1 acidic hydrogen –HCl, HF, HNO 3 Diprotic AcidDiprotic Acid – has 2 acidic hydrogens –H 2 SO 4 Triprotic AcidTriprotic Acid – has 3 acidic hydrogens –H 3 PO 4 All polyprotic acids ionize in steps.

Vocabulary MonohydroxyMonohydroxy Base – has 1 OH - group DihydroxyDihydroxy Base – has 2 OH - groups Trihydroxy BaseTrihydroxy Base - has 3 OH - groups

Vocabulary Strong vs. WeakStrong vs. Weak The terms strong and weak DO NOT refer to concentration. Strong and weak refer to the degree or extent of the ionization. Strong means lots of ionization – almost 100%. Weak means little ionization – 1% or 2%.

Strong Acids Strong acids ionize almost completely:Strong acids ionize almost completely:  HCl  H + + Cl - Lots of H + and Cl -. Very little HCl. Very good electrolytes!

Strong Acids Ionize Almost Totally

Weak Acids Weak acids don’t ionize very much:Weak acids don’t ionize very much:  HC 2 H 3 O 2  H + + C 2 H 3 O 2 - Lots of HC 2 H 3 O 2. Very little H + or C 2 H 3 O 2 -. Weak Electrolytes!

Weak Acids Ionize to a Lesser Extent

Strong Bases Ionize Almost Totally

Weak Bases Undergo Partial Ionization